Electrostatic precipitators, or collectors, are known to the art. In the simplest form, an electrostatic precipitator has a collection electrode that is charged to a relatively high electrostatic potential. Adjacent to, but spaced apart from, the collection electrode is another surface that is electrostatically charged. The collection electrode and the adjacent surface are oppositely charged by a power source, thereby creating an electrostatic field. As air and any constituents of the air move into the electrostatic field, the ionizable constituents of the air are ionized or charged. The ionizable constituents then are attracted to and collect on the collection electrode or in an associated collection medium.
There are two main types of electrostatic precipitators. Dry precipitators perform essentially as described above. Constituents collected on the electrode must be periodically wiped off or otherwise removed from the electrode, or the electrode must be replaced. Wiping mechanisms may be used, or the precipitator must be periodically shut down for cleaning.
Wet or liquid electrostatic precipitators also make use of collection electrodes. In this type of precipitator, however, the collection electrode is periodically or continually washed with a liquid. In these types of precipitators, the collection electrodes are generally tubular or are planar sheets or plates that are arranged either horizontally or vertically. In a vertical arrangement a liquid such as water is conveyed along the upper edges of the sheets or plates such that it flows down the electrodes. The liquid serves to clean the collection electrode(s) on a continuous or periodic basis, avoiding the need to stop the operation of the precipitator to clean or replace electrodes. The liquid is typically conveyed to a disposal system where it can be filtered and otherwise cleaned. Examples of wet precipitators are described in U.S. Pat. No. 3,444,667 to D. D. Mullen and in U.S. Publication No. 2004/0083790A1 of Duane C. Carlson, et al.
There are numerous designs of the two types of precipitators briefly described above and known to the art. The large precipitators are typically used in industrial and commercial applications to clean ventilation air in buildings of dust and other constituents, or to clean exhaust air from chemical and other manufacturing processes. To accomplish this, the precipitators are designed to provide the greatest surface area possible for collection electrodes to increase the efficiency of the cleaning process. These structures require correspondingly large enclosures. Also, precipitators of this size for these purposes require significant amounts of electrical power to create and maintain the electrostatic fields. An industrial device of this type is described in U.S. Pat. No. 5,125,230 to Robert Leonard.
For the foregoing reasons, electrostatic precipitators known to the art are generally limited to use in fixed locations. They are also limited to use at locations having space available for such apparatus, and at locations having sufficient resources, such as available power. These requirements also limit use of such precipitators to locations and to uses justifying the expenditures necessary to install, operate, and maintain such devices. While most precipitators known in the art are limited to specific uses such as cleaning air that is being taken in to a facility or to air that is being exhausted from a facility, there are also sampling precipitators that are used for removing ionized particles for identification.